Why is Pinchas' lineage attributed to Aharon?
Radak: People would not believe that it is the same Pinchas, for this is more than 300 years after 1 [Pinchas killed Zimri in the Midbar]. He lived very long, like Hashem promised "Brisi Shalom" (Bamidbar 25:12). "Brisi Haysah Ito ha'Chayim veha'Shalom" (Mal'achi 2:5) refers to Pinchas. Some say that Pinchas is Eliyahu (Pirkei d'R. Eliezer 47), and some say that Eliyahu is from Binyamin (Bereishis Rabah 71:9); Divrei ha'Yamim 1:8:27-40 supports them. 2
This is like Radak holds, that the Navi is in order. Many Meforshim hold like Seder Olam, that Pesel Michah and Pilegesh b'Giv'ah were shortly after Yehoshua died. Refer to 17:1:1:1-4 and the notes there.
Verse 27 mentions "Eliyah", and verse 40 attributes all mentioned above to Binyamin. One opinion in Bereishis Rabah 71:9 learns from "Eliyahu ha'Tishbi mi'Toshvei Gil'ad" (Melachim 1:17:1) that he was from Gad, but he himself said that he is from Bnei Rachel. Other times, he said that he is from Bnei Leah (Seder Eliyahu Rabah 4), and implied that he is a Kohen (Bava Metzi'a 114b); [at least] one of these was deceptive (Rosh Bava Metzi'a 9:47).
What are the differences in the way they asked Hashem the three times?
Radak: Only the third time, Pinchas asked, and he asked clearly, and the answer was clear. [Before] it was Hashgachah that they fight and be defeated. Now they asked "Im Echdal" - if I will not succeed, I will refrain.
Malbim: The first time they did not ask whether or not they should fight, or if they will win. The second time they asked whether they should fight, but not if they will win. Also now they relied on their strength. Only the third time, they asked in the proper place ("Sham Aron Bris ha'Elokim") and through the proper person (Pinchas). Also, the first two times they prepared to fight before asking. The third time they did not prepare to go, until Hashem told them.
Why did Hashem now promise that they will win?
Malbim: (a) This time, the entire nation went in front of Hashem [to introspect their deeds]. (b) They offered Todos; they realized that they were worthy to die for their sin.
